Free-Standing Lead Zirconate Titanate Nanoparticles: Low-Temperature Synthesis and Densification

Nanocrystalline lead zirconate titanate (PZT) powder with an average particle size between 70 and 110 nm was synthesized using the citrate nitrate (C/N) autocombustion method. Phase-pure perovskite PZT nanoparticles were characterized by XRD, BET surface area, DSC/TGA, and TEM analysis. The crystallite size of the PZT nanoparticles was found to be between 10 and 15 nm. The BET specific surface area increased with increasing C/N ratio during synthesis due to porous structure formation, as the free-standing nanoparticles started to agglomerate. Sintering studies of the pressed pellets made by pure PZT showed >97% theoretical density at 1200 °C for 20 min, whereas the same with 2 wt % ZnO-doped PZT nanoparticles showed 93% theoretical density at as low as 900 °C. Piezoelectric properties were measured using uniaxially pressed compacts at room temperature of these nanoparticles. The room temperature dielectric constant was 550, the piezoelectric constant (d33) was 160 pC/N, and the coupling coefficient (kt) was 0.35 for pure PZT nanoparticles. ZnO-doped PZT nanopowder showed a dielectric constant in the range of 1200-1250, and d33 in the range of 155-170 pC/N and kt in the range of 0.32-0.34. Nanocrystalline PZT powder can be useful for lowtemperature sintering.